Improvements in energy density and cycle life of lead acid batteries are needed to keep them competitive with newer battery concepts. Battery plates of pure lead reinforced with high strength ceramic fiber provide increased energy density since ceramic fibers are lighter than lead. Corrosion resistance (cycle life) is also improved since pure lead is more corrosion resistant than the presently used lead alloys. However, pure lead does not wet alumina surfaces as well as desired.
Alumina can be wetted by aluminum by first depositing salts of cobalt, copper or nickel on the alumina fiber, converting the salts to an oxide, and then reducing the oxide to give a metallic coating. Molten aluminum may then be applied to the metal coated alumina. The use of this general approach in the lead-alumina system has yielded isolated islands of pure lead. Thus, when alumina fiber is treated with lead naphthenate, heated and reduced, the alumina surface bears isolated areas of pure lead.
It has now been found that application of a glass or precursor thereof containing at least about 74% lead oxide (PbO) to alumina filaments affords a coherent, uniform coating of metallic lead after heating and reduction. Such filaments yield excellent composites with pure lead.